Properties of Liquefied Hydrochloric Acid Gas. 547 



white, and remained undissolved in seven days ; on removal it was 

 hard in texture and quite white throughout, and evolved no odour of 

 sulphuretted hydrogen or separation of sulphur on treatment with 

 strong nitric acid. Bright tin evolved no visible gas in the liquid 

 acid ; after ten days' intermittent immersion it was converted, to 

 some depth of its substance, into a bulky white solid with deep fissures. 

 In a second experiment of three days' immersion, similar results 

 occurred ; all the tin was corroded except a minute fibre in the cen- 

 tre, the white solid was imperfectly soluble in water, but instantly 

 soluble in dilute hydrochloric acid. Binoxide of tin in powder did 

 not dissolve in seven days ; the residue was white and insoluble in 

 water. A crystal of protochloride of tin softened before the gas 

 liquefied, and partly dissolved in the liquid acid in four days. Bright 

 metallic thallium evolved no gas in the liquid acid, and was only 

 superficially blackened without further corrosion after three days' 

 immersion. Metallic lead did not evolve visible gas in the lique- 

 fied acid ; it became blackened at first, and in ten days was corroded 

 deeply to a white substance. Red oxide of lead quickly became white 

 in the liquid acid, but did not dissolve in seven days ; it was then 

 quite hard, white throughout, and not readily soluble in water. 

 Precipitated carbonate of lead evolved no visible gas in the liquid 

 acid, and remained undissolved after three days' immersion ; the resi- 

 due evolved no gas by contact with dilute hydrochloric acid. Preci- 

 pitated sulphide of lead in powder produced a faint film of white 

 sublimate in the gas, and by a few hours' immersion in the liquid 

 acid became wholly white ; it did not dissolve during seven days, 

 and was then quite white throughout, and not readily soluble in 

 water. Yellow iodide of lead did not dissolve in seven days, but be- 

 came of a purplish brick-brown colour and evolved a strong odour 

 of free iodine ; it produced yellowish-brown stains upon paper. 

 Yellow chromate of lead evolved at first (in the gaseous acid) a small 

 quantity of deep-red vapour, which condensed as a red moisture 

 near it on the tube ; the chromate became white in the gas, and 

 did not dissolve in the liquid acid in three days ; it was then a soft 

 white solid, not freely soluble in water, and imparted a faint greenish 

 tint to water. 



A minute fragment of iron remained bright, and evolved no gas 

 when the liquid acid came into contact with it ; after nine days of 

 intermittent immersion it was only slightly tarnished, and on removal 

 from the acid was found otherwise unaltered. A fragment of fused 

 sulphide of iron produced a faint film of whitish sublimate at first, 

 but evolved no bubbles of gas on contact with the liquid acid ; it did 

 not dissolve or alter in appearance. A second fragment constantly 

 immersed during three days behaved similarly; it was as hard as 

 before immersion, and evolved sulphuretted hydrogen freely in hot 

 dilute sulphuric acid. A crystal of green vitriol became yellowish 

 white and opaque in the liquid acid, but did not diminish in volume 

 in six days; the residue was a soft opaque yellowish-white solid. 

 Oxide of cobalt in powder exhibited no change or solution during 

 three days ; on removal it was found to be very hard, of a light- 



